Ichthyosporidium sp. Schwartz, 1963, Parasite of the Fish Leiostomus xanthurus,Is a Microsporidian*

SYNOPSIS. Schwartz identified a protozoan, parasite of the marine fish Leiostomus xanthurus as a haplosporidian belonging to genus Ichthyosporidium Caullery and Mesnil, 1905. Now, a coiled polar filament in the spore of that organism has been clearly recognized in certain PAS preparations which were used in the original study. The parasite is, therefore, a microsporidian rather than a haplosporidian. The generic characters of this and other protozoans still in genus Ichthyosporidium need further study.     

Fine Structure of the Cyst and Some Sporulation Stages of Ichthyosporidium (Microsporida)*

SYNOPSIS. Ichthyosporidium sp. Schwartz, 1963, apparently identical with the type species, I. giganteum (Thélohan, 1895) Swarczewsky, 1914, was studied with the electron microscope. Only late stages, a mature cyst containing sporulation stages and a cyst in the terminal (necrotic) stage were observed. The cyst, originating from host tissue, is a highly organized structure that is integrated with the surrounding connective tissue by means of numerous conspicuous processes. It is interpreted as essentially a manifestation of a defensive reaction of the host that is elicited by the parasite and then used to its advantage. Eventually the cyst dies and disintegrates. This type of cyst, peculiar among those associated with microsporidia, may be regarded as a distinctive character of the poorly defined genus Ichthyosporidium. Other observations let to an hypothesis which reconciles several different views regarding the identity of the Golgi complex. According to this new interpretation, these different views concern different aspects af the total complex. When all such views are integrated, a “classical Golgi” can be recognized in the presporoblastic stages and the “primitive Golgi” concept disappears. This “classical Golgi” then becomes highly modified during spore morphogenesis, giving rise to many of the internal organelles that are peculiar to the spore.     

The ultrastructure and reproduction of Amphiamblys capitellides (Microspora, Metchnikovellidae), a parasite of the gregarine Ancora sagittata (Apicomplexa, Lecudinidae), with redescription of the species and comments on the taxonomy

The ultrastructural cytology and reproduction of the hyperparasitic microsporidium Amphiamblys capitellides (Caullery and Mesnil, 1897) is described. Merogonial reproduction was not observed. The sporogony comprises two sequences: a sac-bound sporogony in close contact with the cytoplasm of the host and a free sporogony in parasitophorous vacuoles. The free sporogony, which probably precedes the sac-bound, yields a small number of rounded spores. The sac-bound sporogony is polysporoblastic, generating two rows of elongated spores. All stages have isolated nuclei. Both spore types have an extrusion apparatus of the metchnikovellidean type, with a polar sac devoid of anchoring disc, a polar filament with one manubroid and one bulbous part, and a posterior semicircular membrane fold enclosing rounded or tubular structures. Hosts are gregarines of the species Ancora sagittata living in the intestine of polychaetes of the genus Capitella, probably the species Capitella giardi. The cytology, life cycle and classification are discussed. The species is redescribed and the diagnosis of the genus Amphiamblys Caullery and Mesnil, 1914 is emended.     

The demise of Leptotheca Thélohan, 1895 (Myxozoa: Myxosporea: Ceratomyxidae) and assignment of its species to Ceratomyxa Thélohan, 1892 (Myxosporea: Ceratomyxidae), Ellipsomyxa K?ie, 2003 (Myxosporea: Ceratomyxidae), Myxobolus Bütschli, 1882 and Sphaerospora Thélohan, 1892 (Myxosporea: Sphaerosporidae)

A revision of Leptotheca Thélohan, 1895 is presented. The boundaries that separate Leptotheca from Ceratomyxa Thélohan, 1892 and Sphaerospora Thélohan, 1892 are vague and have been highlighted as an area of concern within myxosporean classification. A survey of the literature revealed 63 species that are currently assigned to Leptotheca and a further 11 species that have been relegated as synonyms in Ceratomyxa, Sphaerospora or Myxobolus Bütschli, 1882. The placement of some species in the genus is unclear and demonstrates the need for a revision. The type-species of Leptotheca (L. agilis Thélohan 1892) has many Ceratomyxa-like characters, such that a minor amendation of the diagnosis of Ceratomyxa will then accept the type-species of Leptotheca, rendering the latter genus its synonym. We propose the suppression of Leptotheca, with all species currently assigned to that genus reassigned to Ceratomyxa, Ellipsomyxa K?ie, 2003, Myxobolus or Sphaerospora on the basis of appropriate morphological and biological traits. The diagnoses of Ceratomyxa and Ellipsomyxa are amended appropriately. Molecular analysis may change the placement of some species in the future; however, the aim of this review was to eliminate the ambiguity of assignment of species in the genera Leptotheca, Ceratomyxa and Sphaerospora by suppressing Leptotheca.     

Small subunit ribosomal DNA phylogeny of microsporidia with particular reference to genera that infect fish

Molecular data have proved useful in the study of microsporidia phylogeny. Previous studies have shown that there are several important differences between phylogenies based on rRNA and morphological data. In the present study, small subunit (SSU) rDNA sequences were obtained from 7 different fish-infecting microsporidia from 4 different genera (Glugea Thélohan, 1891, Loma Morrison and Sprague, 1981, Pleistophora Gurley, 1893, and Spraguea Weissenberg, 1976). The lengths of the SSU rDNA genes in these species were between 1,332 and 1,343 base pairs. Phylogenetic analysis was performed using parsimony, maximum likelihood, and Kimura 2-parameter with neighbor joining. The analyses revealed that the microsporidia could be divided into 3 major groups. With the exception of Nucleospora salmonis Hedrick, Groff, and Baxa, 1991, all the microsporidia infecting fishes occurred in the same group. The analysis showed that Pleistophora mirandellae Vaney and Conte, 1901 and Pleistophora aguillarum Hoshina, 1951 are not species of Pleistophora. Furthermore, the analysis showed that Loma is not a member of Glugeidae Thélohan, 1892.     

Fine structure of the microsporidan Abelspora portucalensis gen.n., sp.n. (Microsporida) parasite of the hepatopancreas of Carcinus maenas (Crustacea,Decapoda)

A new species of a microsporidan, Abelspora portucalensis, was found in the hepatopancreas of Carcinus maenas, forming white xenomas. Each xenoma seems to consist of an aggregate of hypertrophic host cells in which the parasite develops and proliferates. This cytozoic microsporidan being characterized by one uninucleate schizont giving rise to two sporonts, each originating two sporoblasts, resulting in two spores within a persistent sporophorous vacuole (pansporoblast) should be included in a new family Abelsporidae. In fresh smears most spores were 3.1–3.2 μm long and 1.2–1.4 μm wide. Fixed, stained, and observed in SUS mature spores measured 3.1 ± 0.08 × 1.3 ± 0.06 μm (n = 25 measurements). Spore cytoplasm was dense and granular, polyribosomes were arranged in helicoidal tape form. The polar filament was anisofilar and consisted of a single coil with 5–6 turns. The anchoring disc and and the anterior zone of the filament are surrounded by the polaroplast composed of two usual zones. In the anterior zone, the membrane of the polar filament is in continuity with the membranes of the polaroplast. The appearance of a microsporidan with described nuclear divisions in life cycle, spores shape and size, polaroplast and polar filament morphology and identity of the host suggests that we may erect a new genus Abelspora and a new species A. portucalensis (Portugal = Portucalem).     

Synopsis of the species of Ceratomyxa Thélohan, 1892 (Myxozoa: Myxosporea: Ceratomyxidae)

A synopsis of the species of Ceratomyxa Thélohan, 1892 (Myxozoa: Myxosporea: Ceratomyxidae), including a total of 147 species, is presented. For each species the relevant morphological and morphometric data are indicated, as well as the site of infection within the host and the original hosts and locality. A diagrammatic illustration of the spores is also provided.     

Internal ultrastructure of spores of microsporidans isolated from the Silkworm,Bombyx mori

Nosema bombycis, two Nosema spp., and a Pleistophora sp. were propagated in the silkworm and the fine structures of their spores were studied. The morphology of the polaroplast, the appearance of the nucleus, and the number of coils in the polar filament differed among the spores of the four species. The spores of the three Nosema species, however, had several identical components; e.g., the polaroplast was made up of two parts, they had two nuclei, and the ribosome arrangement was similar. On the other hand, the spore of Pleistophora sp. had a polaroplast composed of three parts, a single nucleus, and ribosomes arranged around the polar filament. Thus the fine structures of the spore differentiate microsporidan species.     

Henneguya michiganensis n. sp. (Cnidaria: Myxosporea) from the gills of muskellunge Esox masquinongy Mitchill(Esociformes: Esocidae)

Systematic Parasitology - Henneguya Thélohan, 1892 is the second most species rich genus of myxozoans, with reports from freshwater and marine fish worldwide. In the Great Lakes...     

Ichthyosporidium weissii n. sp. (Microsporidia) infecting the arrow goby (Clevelandia ios)

Gonadal infections by a novel microsporidium were discovered in 34% (13/38) of arrow gobies, Clevelandia ios, sampled over a 3‐yr period from Morro Bay Marina in Morro Bay, California. Gonadal tumors had been reported in arrow gobies from this geographic area. The infected gonads, found primarily in females, typically appeared grossly as large, white‐gray firm and lobulated masses. Histological examination revealed large, multilobate xenomas within the ovaries and no evidence of neoplasia. Typical of the genus Ichthyosporidium, the large xenomas were filled with developmental stages and pleomorphic spores. Wet mount preparations showed two general spore types: microspores with mean length of 6.2 (7.0–4.9, SD = 0.6, N = 20) μm and mean width of 4.3 (5.3–2.9, SD = 0.8) μm; and less numerous macrospores with mean length of 8.5 (10.1–7.1, SD = 1.0, N = 10) μm and mean width of 5.5 (6.2–4.8, SD = 0.5) μm. Transmission electron microscopy demonstrated stages consistent with the genus and 35–50 turns of the polar filament. Small subunit rDNA gene sequence analysis revealed that the parasite from arrow gobies was most closely related to, but distinct from Ichthyosporidium sp. based on sequences available in GenBank. We conclude that this microsporidium represents a new species of Ichthyosporidium, the first species of this genus described from a member of the family Gobiidae and from the Pacific Ocean.     

A new species of Haplosporidium Caullery & Mesnil, 1899 in the marine false limpet Siphonaria lessonii (Gastropoda: Siphonariidae) from Patagonia

A new species of Haplosporidium Caullery & Mesnil, 1899 parasitising the pulmonate gastropod Siphonaria lessonii Blainville in Patagonia, Argentina, is described based on morphological (scanning and transmission electron microscopy) and sequence (small subunit ribosomal RNA gene) data. Different stages of sporulation were observed as infections disseminated in the digestive gland. Haplosporidium patagon n. sp. is characterised by oval or slightly subquadrate spores with an operculum that is ornamented with numerous short digitiform projections of regular height, perpendicular to and covering its outer surface. The operculum diameter is slightly larger than the apical diameter of the spore. Neither the immature nor mature spores showed any kind of projections of the exosporoplasm or of the spore wall. Regarding phylogenetic affinities, the new species was recovered as sister to an undescribed species of Haplosporidium Caullery & Mesnil, 1899 from the polychaete family Syllidae Grube from Japanese waters. The morphological characters (ornamentation of the operculum, spore wall structure, shape and size of spores, and the lack of spore wall projections) corroborate it as an as yet undescribed species of Haplosporidium and the first for the phylum in marine gastropods of South America. Siphonaria lessonii is the only known host to date.     

Ultrastructural Study of the Development of Pleistophora schubergi Zwölfer, 1927 (Protozoa,Microsporida) in Larvae of the Spruce Budworm,Choristoneura fumiferana and Its Subsequent Taxonomic Change to the Genus Endoreticulatus

This study demonstrates that Pleistophora schubergi Zwölfer, 1927, a microsporidium originally isolated from the midgut epithelium of Nygmia phaeorrhoea Don (Euproctis chrysorrhoea L.) and Porthetria dispar L., and subsequently reported in several other insects including the spruce budworm, Choristoneura fumiferana (the host used in this investigation), does not belong in the genus Pleistophora Gurley, 1893. Pleistophora schubergi lacks the major features that are characteristic of Pleistophora typicalis, the type species of this genus. A comparison of ultrastructural observations reported for the type species of the genus Pleistophora, P. typicalis, and our observations of P. schubergi revealed significant differences. A thick (0.5 μm) amorphous coat, derived from parasite secretions and deposited external to the parasite plasmalemma, surrounds all developmental stages in P. typicalis. Double membranes, derived from host rough endoplasmic reticulum cisternae encircle the parasite plasmalemma of all developmental stages in P. schubergi. The sporophorous vesicle encases the spores in P. typicalis, and originates from the parasite-secreted coat that is present around meronts. In P. schubergi, the host endoplasmic reticulum cisternae form the envelope that surrounds the meronts. Moreover, the sporophorous vesicle envelope in P. typicalis persists around groups of spores, while in P. schubergi this envelope breaks easily to release the spores in the host cytoplasm. By comparing the characteristics of the microsporidium found in the spruce budworm with those of the recently created polysporous genera that sporulate within a vesicle, we found that P. schubergi does belong in the new genus Endoreticulatus Brooks et al. 1988, and consequently rename it Endoreticulatus schubergi (Zwölfer, 1927) n. comb.     

A new species of Glugea Thélohan, 1891 in the red sea bream Pagrus major (Temminck & Schlegel) (Teleostei: Sparidae) from China

A new microsporidian species is described from farmed red sea bream Pagrus major (Temminck & Schlegel) (Teleostei: Sparidae). Large numbers of spherical whitish xenomas were observed throughout the visceral organs of the host. Histological examination showed that the microsporidia caused several xenomas that were embedded in the intestinal muscularis externa or submucosa. Light and transmission electron microscopy examination of the spores also revealed morphological features typical of species of Glugea Thélohan, 1891. This microsporidian parasite has two different types of mature spores: microspores and macrospores. The spores are elongate-ovoid, with a large posterior vacuole. The polaroplast is bi-partite, with anterior and posterior parts comprising densely packed lamellae and loose membranes, respectively, and occupies approximately the anterior half of the spore. The polar filament is anisofilar, with 12–13 coils in a single layer almost touching the posterior spore wall. Comparison of the small subunit rDNA sequences revealed 92.7–98.1% identity with the sequences available from other Glugea spp. from piscine hosts. Phylogenetic analysis demonstrated that the microsporidian species studied clustered within the Glugea clade with strong support. Based on the differences in the morphological characteristics and molecular data, the microsporidian infecting P. major is considered to represent a species new to science, Glugea pagri n. sp.     

Structure and Development of a Marine Actinosporean, Sphaeractinomyxon ersei n. sp. (Myxozoa)

ABSTRACT This is the first ultrastructural study of the development of a marine actinosporean and of a species belonging to the genus Sphaeractinomyxon Caullery & Mesnil, 1904. S. ersei n. sp. is described from a limnodriloidine oligochaete, Doliodrilus diverticulatus Erséus, 1985, from Moreton Bay. Queensland, Australia. Development is asynchronous, there being all stages from two-celled pansporoblasts through to mature spores present simultaneously within a host. Spores develop in groups of eight within pansporoblasts in the coelom and when mature are located also in the intestinal lumen. The primordial spore envelope and sporoplasm develop separately in the pansporoblast until the polar filament is formed within the polar capsule and the capsulogenic cell cytoplasm has begun to degrade. The sporoplasm then enters the spore through a separated valve junction. Mature spores are triradially symmetrical with three centrally located polar capsules and a single binucleate sporoplasm with about 46 germ cells. Swellings or projections of the epispore do not occur when spores exit the host and contact sea water.     

Description of Chytridiopsis Trichopterae N. Sp. (Microspora, Chytridiopsidae), A Microsporidian Parasite of the Caddis Fly Polycentropus Flavomaculatus (Trichoptera, Polycentropodidae), With Comments On Relationships Between the Families Chytridiopsidae and Metchnikovellidae

ABSTRACT. The microsporidium Chytridiopsis trichopterae n. sp., a parasite of the midgut epithelium of larvae of the caddis fly Polycentropus flavomaculatus found in southern Sweden, is described based on light microscopic and ultrastructural characteristics. All life cycle stages have isolated nuclei. Merogonial reproduction was not observed. the sporogony comprises two sequences: one with free spores in parasitophorous vacuoles, the other in spherical, 5.6-6.8 μm wide, sporophorous vesicles which lie in the cytoplasm. the free sporogony yields more than 20 spores per sporont. the vesicle-bound sporogony produces 8, 12 or 16 spores. the envelope of the sporophorous vesicle is about 82 nm thick and layered. the internal layer is the plasma membrane of the sporont; the surface layer is electron dense with regularly arranged translucent components. Both spore types are spherical. They have an ～ 35-nm thick spore wall, with a plasma membrane, an electron-lucent endospore, and an ～ 14-nm thick electron-dense exospore. the polar sac is cup-like and lacks a layered anchoring disc. the polar filament is arranged in two to three isofilar coils in the half of the spore opposite the nucleus. the coupling between the polar sac and the polar filament is characteristic. the surface of the polar filament is covered with regularly arranged membraneous chambers resembling a honeycomb. There is no polaroplast of traditional type. the cytoplasm lacks polyribosomes. the nucleus has a prominent, wide nucleolus. the two spore types have identical construction, but differ in dimensions and electron density. Free living spores are about 3.2 μm wide, the diameter of the polar filament proper is 102-187 nm, the chambers of the honeycomb are 70-85 nm high, and the polar sac is up to 425 nm wide. Living spores in the vesicle-bound sporogony are about 2.1 μm wide, the polar filament measures 69-102 nm, the chambers of the honeycomb are about 45 nm high, and these spores are more electron dense. Comparisons of cytology (especially the construction of the spore wall and the polar filament and associated structures) and life cycles reveal prominent differences among the Chytridiopsis-like microsporidia, and close relationships between the families Chytridiopsidae and Metchnikovellidae.     

<Emphasis Type="Italic">Myxobolus imparfinis</Emphasis> n. sp. (Myxozoa: Myxosporea), a new gill parasite of <Emphasis Type="Italic">Imparfinis mirini</Emphasis> Haseman (Siluriformes: Heptapteridae) in Brazil

A new species of myxozoan, Myxobolus imparfinis n. sp. is described based on material from the gills of Imparfinis mirini (Haseman) (Heptapteridae). Mature myxospores are round, measuring 7.1–8.4 (7.9 ± 0.3) μm in length, 4.5–6.2 (5.5 ± 0.5) μm in width and 3.1–4.2 (3.7 ± 0.3) μm in thickness. The polar capsules are of unequal size, the larger polar capsule measuring 3.4–4.5 (3.9 ± 0.3) μm in length and 1.4–2.0 (1.7 ± 0.1) μm in width and the smaller capsule measuring 3.1–3.8 (3.4 ± 0.2) μm in length and 1.2–1.8 (1.5 ± 0.2) μm in width. The polar filament presents 6–7 coils. Spores had a prevalence of infection of 75% (6/8). In histological analyses we detected the development site of spores in primary filaments, in afferent branchial artery, thus classifying the type of infection to the filamental type and vascular subtype. The phylogenetic analyses of a dataset including species Myxobolus Bütschli, 1882 and Henneguya Thélohan, 1892 from South America recovered M. imparfinis n. sp. as a sister species of Myxobolus flavus Carriero, Adriano, Silva, Ceccarelli & Maia, 2013. To our knowledge, this is the first record of a myxozoan species parasitising I. mirini.     

Phylogeny of Myxobolidae (Myxozoa) and the evolution of myxospore appendages in the Myxobolus clade

Genera Myxobolus Bütschli, 1882 and Henneguya Thélohan, 1892 (Myxobolidae) are specious myxozoan genera. They comprise nearly half of overall known myxozoan species diversity. A typical spore feature of Henneguya is the presence of two caudal appendages of the spore valves, which distinguishes them from species of the genus Myxobolus. Several Myxobolus spp., however, were reported to show aberrant spores with Henneguya-like caudal appendages. We found such aberrant spores in Myxobolus tsangwuensis and Myxobolus wulii. We studied the ultrastructure of M. wulii and Myxobolus oralis spores with caudal appendages by transmission electron microscopy (TEM). TEM of these aberrant spores revealed that their caudal appendages have the same ultrastructure as the appendages of Henneguya spp. Small caudal appendages of M. wulii spores observed only on TEM suggested that this character may be often overlooked and more Myxobolus species potentially have the ability to express the caudal appendages on the myxospore. In order to trace the evolution of this character, we performed broad phylogenetic analysis of all species of the family Myxobolidae which are available in GenBank including nearly 300 taxa. We found at least eight independent evolutionary origins of spores with two appendages, three origins of a single appendage and 12 apparent secondary losses of the spore projections. Therefore, genus Henneguya with typical two-tailed myxospores is polyphyletic, however a majority of its species has a common ancestor and groups in the second largest subclade of the Myxobolus clade. We also mapped the biological characteristics (host, site of infection and environment) of Myxobolidae species on the phylogenetic tree. We revealed an evident host-associated evolutionary pattern in all parts of the Myxobolus clade with a distinct and species-rich subclade containing almost exclusively species infecting species of the Order Cypriniformes.     

Taxonomic notes on African Orthotrichaceae 2: Macrocoma – new synonymy and first report of multicellular spores

Type material of two poorly known species of Macromitrium, described from East Africa and Madagascar, was examined and both were found to belong to the genus Macrocoma. Macromitrium megalosporum Thér. & Naveau was found to be morphologically very close to Macrocoma abyssinica (Müll.Hal.) Vitt., with the only significant difference between these taxa being the large multicellular spores of M. megalosporum, which is also the first report of multicellular spores for the genus Macrocoma. This name is here transferred to Macrocoma as Macrocoma abyssinica var. megalospora (Thér. & Naveau) Wilbraham comb. nov. Macrocoma abyssinica var. megalospora is reported new for the Comoros, which is the first record for the species in the East African Islands. Macromitrium adelphinum Cardot in Grandidier was found to be conspecific with Macrocoma tenuis (Hook. & Grev.) Vitt. subsp. tenuis and an appropriate synonymy is proposed. Macrocoma tenuis. subsp. tenuis is also reported here new to the Comoros.     

Relatedness of novel species of Myxidium Bütschli, 1882, Zschokkella Auerbach, 1910 and Ellipsomyxa Køie, 2003 (Myxosporea: Bivalvulida) from the gall bladders of marine fishes (Teleostei) from Australian waters

During a parasitological survey, Myxidium-like spores were identified in the gall bladders of marine fishes from Australian waters. This paper describes four novel species of Ellipsomyxa Køie, 2003, three novel species of Myxidium Bütschli, 1882 and six novel species of Zschokkella Auerbach, 1910 from teleosts from Australian waters using a combination of morphological, biological and molecular characters. Phylogenetic analyses showed a monophyletic relationship of all Ellipsomyxa spp. sequences with Sigmomyxa sphaerica (Thélohan, 1895) and Myxidium queenslandicus Gunter & Adlard, 2008 as sister species to the clade. The validity of genus Sigmomyxa Karlsbakk & Køie, 2012 is discussed. In phylogenetic analyses, the novel species of Myxidium fell within the ‘marine’ clade of Fiala (2006). However, the novel species of Zschokkella fell within the ‘freshwater’ clade of Fiala (2006) and formed a distinct clade with all other sequences of Zschokkella spp. from the gall bladder of marine fish and a sequence of a species of Myxobolus Bütschli 1882, also from the gall bladder of a marine fish. This is the second distinct marine lineage to emerge within the freshwater clade.     

Glugea gasti sp. n., a Microspridan Pathogen of the Boll Weevil Anthonomus grandis1,2,3

SYNOPSIS. Glugea gasti sp. n., a microsporidan pathogen of Anthonomus grandis Boheman (the boll weevil), is described and a probable life cycle presented. The alimentary canal, and probably the mesenteron 1st, is the initial site of infection, altho the disease later becomes generalized thruout most body tissues. Binucleate sporoplasms initiate the 1st schizogonic phase, characterized by mono- and bi-nucleate schizonts. The 2nd schizogonic phase is characterized by mono-, bi- and quadrinucleate schizonts, by prolific multiplication, by the dense compact nuclei early in this phase, and late in this phase by larger schizonts with less dense vesicular nuclei. This phase terminates in formation of diplokarya. The sporogonic phase is characterized by combination of the 2 nuclei in the diplokaryon followed by nuclear divisions in a sequence closely resembling meiosis. Two sporoblasts are produced from each sporont. Mature spores in wet mounts by phase contrast were 4.3 ± 0.3 μ long by 2.3 ± 0.2 μ wide. The polar filament averaged 76 μ long. Mature spores were present about 24 hours after infection. Some observations are presented on an external filament extending from one pole of the spore to host tissue and other events during the process of spore morphogenesis.